1. Field of the Invention
The invention relates to the field of video and audio signal monitoring and test equipment, and in particular concerns a signal processor with two analog composite video inputs, two serial digital video inputs (compliant with ITU-R BT.601 SMPTE 259M standards at 270 Mb/s, 50 Hz and 60 Hz field rates, also called CCIR 601) as well as two stereo analog audio inputs. The signal processor is operable selectively and/or simultaneously to display video images, graphic video waveform information, graphic vector data and audio information in high resolution form. The invention is useful in connection with graphics production, mixed format and video production and post production facilities, and can replace two waveform monitors, two vectorscopes, an audio test set and two standard video monitors.
2. Prior Art
Standard video signals are generally displayed on either television sets or composite video monitors in color or black and white. For color, the standard color composite video signal is an analog signal that electrically represents the brightness or luminance, saturation and color hue or chrominance of a complete video picture or frame, divided into sequential individual picture elements (pixels) of a raster scanned display. A pixel is the smallest discrete area of a television or video picture, each including adjacent red, blue and green phosphors. In addition, the signal includes synchronizing information associated with controlling raster scanning, such as blanking and maintaining the correct phase relationship between the signal and deflection of the electron beam for scanning accurately over the respective colored parts of the successive pixels.
Monitors compliant with various video standards such as NTSC, PAL and SECAM are available and display a video image in an interlaced format having specific timing. For example, an NTSC compliant composite video signal is displayed with 525 lines per frame at 30 frames per second. Each frame is composed of two interlaced fields of 262.5 lines completed at a field rate of 59.94 Hz.
Three basic types of synchronizing information are contained in the signal, namely horizontal sync pulses at the line rate, vertical sync pulses at field rate and a color burst during horizontal blanking. The color burst typically controls a phase locked loop and provides a frequency and phase reference for correctly decoding the color information by illuminating the correct colored phosphors with the cathode ray electron beam at the correct time.
Video production equipment advantageously includes various forms of video and audio signal monitoring and measurement equipment useful to verify the integrity of the signal being processed, for example for adjusting equipment to certain standards when processing a test pattern or for generally monitoring characteristics of the program. The composite graphic video waveform can be viewed graphically, for example, using an oscilloscope triggered by the horizontal sync to provide a two dimensional representation of the video signal in Cartesian coordinates (X axis--time, Y axis--amplitude) when processing a test pattern having vertical color bars. Alternatively a modified oscilloscope with specific time bases and amplitude scales is used.
The color content of the video signal is represented by phase relationship to the subcarrier synchronized to the color burst. Accordingly, color information is advantageously displayed graphically in a polar plot using a vectorscope. A vectorscope is generally a specialized oscilloscope operable to display a Lissajous pattern in which both the X and Y axis of the display represent luminance information (e.g., red minus luminance plotted against blue minus luminance). The vectorscope is useful in setting or monitoring timing, phase and amplitude parameters of a video signal to match standard color test patterns.
Audio information which accompanies a television video signal is generally displayed on moving needle galvanometers or LED bar displays with scales calibrated in dB.
Test instruments such as the Videotek VTM-100, VTM-100D and the Tektronix WVR500 provide for the simultaneous display of video image information, waveform, vector and audio graphic display information in interlaced format on an NTSC or PAL monitor. The use of standard interlaced displays for simultaneous display of such information severely limits the clarity and detail of the video images, rasterized waveforms, vectorscope and audio graphic display information. It would be desirable to provide a simple and efficient means to display video images, waveforms, vectorscope and audio graphic display information with increased clarity and detail, and preferably selectively and simultaneously.